Re: A few user-level questions on Streaming Replication and pg_upgrade

Gurjeet Singh wrote:
> On Tue, Jul 19, 2011 at 8:45 PM, Bruce Momjian <bruce(at)momjian(dot)us> wrote:
>
> > Gurjeet Singh wrote:
> >
> > [ CC to general removed --- emailing only hackers; cross-posting is
> > frowned upon. ]
> >
>
> I thought these questions were of interest to the general public too.

What I usually do is to discuss on hackers and post a summary of
information 'general' would find interesting.

> > > .) Is Streaming Replication supported across minor releases, in reverse
> > > direction; e.g. 9.0.3 to 9.0.1
> > >
> > > I think the answer is "it depends", since it would depend upon
> > whether
> > > any SR related bug has been fixed in the 'greater' of the minor releases.
> > >
> > > I am assuming that smaller minor release to bigger minor release will
> > > always be supported (e.g. 9.0.1 to 9.0.3)
> >
> > Yes.
>
>
> I am assuming that's a "yes" to both the directions: older -> newer , and
> newer -> older minor releases.

Yes, I believe both directions would work unless we mentioned it the
release notes, in which cases it might not work, or might work older to
newer but newer to older.

> > We could mention in the minor release notes if we break streaming
> > replication for a minor release --- or someone will tell us when we do.
> >
>
> I am pretty sure the Postgres community would notify its user base via
> release notes.

We will if we know it, but it is possible to have rare cases where we
don't find out until after the minor release.

> > > .) How reliable is `pg_upgrade -c` (dry run) currently; that is, how
> > > accurate is pg_upgrade at predicting any potential problem with the
> > eventual
> > > in-place upgrade.
> > >
> > > I'd say it is as reliable as it gets since this is the official tool
> > > supported by the project, and it should not contain any known bugs. One
> > has
> > > to use the latest and greatest 'minor' version of the tool for the major
> > > release they are upgrading to, though.
> >
> > Well, we make no guarantees about the software at all, so it is hard to
> > make any guarantee about pg_upgrade either.
> >
>
> :) Given the BSD-style license, that's a fair point.

I just found out, thanks to EnterpriseDB testing, that pg_upgrade -l
doesn't work on Windows. I will post the fix in an hour for all
released versions of pg_upgrade. You will find it entertaining that -l
works in check mode but not in actual upgrade mode.

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

+ It's impossible for everything to be true. +